1. Field of the Invention
The present invention relates to a three-dimensional printing device.
2. Description of the Related Art
There are conventional three-dimensional printing devices for printing a three-dimensional printed object by irradiating a liquid photo-curable resin contained in a vat with light and curing the photo-curable resin.
A three-dimensional printing device of this type prepares cross-sectional shapes of a three-dimensional printed object, and cures the photo-curable resin so as to successively deposit resin layers whose shapes correspond to the cross-sectional shapes, thereby printing the three-dimensional printed object. As shown in Japanese Laid-Open Patent Publication No. 2003-39564, for example, a three-dimensional printing device includes a platform with an opening therein, a resin vat placed on the platform and containing a photo-curable resin therein, and a holder that is disposed above the vat and can be moved up and down. An optical device disposed below the platform, includes a light source outputting light, a mirror, etc. Light output from the light source is reflected by the mirror and passes through the opening of the platform, irradiating the photo-curable resin in the vat. A portion of the photo-curable resin contained in the vat that is irradiated with light cures.
By controlling the position of light irradiation, it is possible to appropriately change the position at which the resin cures, and thus to form a resin layer having a desired cross-sectional shape. By successively raising the holder, desired cross-sectional shapes are formed continuously in a downward direction. Thus, it is possible to print a desired three-dimensional printed object.
Now, when printing three-dimensional printed objects using the same resin vat over a long period of time, portions of the vat that are irradiated with light may become clouded white (hereinafter this will be referred to as “clouding”). When the clouded vat is irradiated with light in order to cure the photo-curable resin in the vat, the light is partially blocked by the clouded portions of the vat, thereby failing to appropriately cure portions of the photo-curable resin around the clouded portions of the vat. Then, an intended cross-sectional shape may not be formed, and the quality of the printed object may lower.